Mounting arrangement

ABSTRACT

An apparatus for supplying breathable gas for assisted respiration includes a casing portion having a gas flow path between a gas inlet and a gas outlet, a rotor disposed within the casing portion and in fluid communication with and positioned between the gas inlet and the gas outlet, an electric motor coupled to the rotor, and a sealed inflatable cushion having a base surface structured to support the casing portion and the electric motor thereon. The inflatable cushion is in fluid communication with the gas outlet to thereby at least one of inflate and maintain inflated the inflatable cushion.

This is a Continuation of U.S. application Ser. No. 09/489,229 filed on Jan. 21, 2000, now U.S. Pat. No. 6,315,526, Nov. 13, 2001 the entirety of which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a mounting arrangement and in particular a mounting arrangement for a fluid displacement device.

The invention has been developed primarily for mounting an electric motor and blower assembly within the housing of a Continuous Positive Airway Pressure (CPAP) treatment apparatus used in the CPAP treatment of, for example, Obstructive Sleep Apnea (OSA) and other ventilatory assistance treatments such as Non Invasive Positive Pressure Ventilation (NIPPV) and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use and is equally suited in mounting various types of fluid displacement devices including fans, pumps and the like.

BACKGROUND OF THE INVENTION

CPAP treatment is a common ameliorative treatment for breathing disorders including OSA. CPAP treatment, as described in U.S. Pat. No. 4,944,310, provides pressurised air or other breathable gas to the entrance of a patient's airways at a pressure elevated above atmospheric pressure, typically in the range 4-20 cm H₂O.

It is also known for the level of treatment pressure to vary during a period of treatment in accordance with patient need, that form of CPAP being known as automatically adjust nasal CPAP treatment, as described in U.S. Pat. No. 5,245,995.

NIPPV is another form of treatment for breathing disorders which can involve a relatively higher pressure of gas being provided in the patient mask during the inspiratory phase of respiration and a relatively lower pressure or atmospheric pressure being provided in the patient mask during the expiratory phase of respiration.

In other NIPPV modes the pressure can be made to vary in a complex manner throughout the respiratory cycle. For example, the pressure at the mask during inspiration or expiration can be varied through the period of treatment.

Typically, the ventilatory assistance for CPAP or NIPPV treatment is delivered to the patient by way of a nasal mask. Alternatively, a mouth mask or full face mask or nasal prongs can be used. In this specification any reference to a mask is to be understood as incorporating a reference to a nasal mask, mouth mask, full face mask or nasal prongs.

In this specification any reference to CPAP treatment is to be understood as embracing all of the above described forms of ventilatory treatment or assistance.

A CPAP apparatus broadly comprises a flow generator constituted by a continuous source of air or other breathable gas such as a hospital piped supply or a blower. The gas supply is connected to a conduit or tube, which in turn is connected to a patient mask which incorporates, or has in close proximity, an exhaust to atmosphere for venting exhaled gases. The blower is typically driven by an electric motor controlled by a servo-controller which is in turn under the control of a microcontroller unit.

The blower/motor assembly has hitherto been either directly mounted to the chassis or body of the CPAP apparatus, or isolated therefrom, by foam or other elastomeric sheets or moulded components to dampen vibration and minimise radiated noise. The use of foam sheets is time consuming and expensive as several sections of sheet may have to be installed. The installation of moulded foam components is less time consuming but they are more expensive to produce.

Other rotating or reciprocating machines use inflatable cushions to dampen the machine's vibration by interposing one or more of the inflatable cushions between the machine and its chassis, housing, ground or other supporting structure. There are two main types of inflatable cushions.

A first type is inflated or filled and thereafter sealed. A disadvantage of this type is they leak and collapse if punctured or otherwise damaged. As a consequence, they are not suitable for use in CPAP apparatus which are sealed during manufacture and not serviceable by customers.

A second type rely on a dedicated constant or intermittent fluid supply to maintain inflation. A disadvantage of this type is the additional complexity and costs associated with the dedicated fluid supply. This second type is also particularly unsuitable for CPAP treatment apparatus which are desirably made as small and light-weight as possible.

It is an object of the present invention to substantially overcome or at least ameliorate one or more of the deficiencies of the prior art.

SUMMARY OF THE INVENTION

Accordingly in a first aspect, the present invention provides a mounting arrangement for a fluid displacement device, the mounting arrangement comprising an inflatable cushion device adapted to support the fluid displacement device and in fluid communication with the fluid displacement device, whereby a portion of the fluid displaced by the fluid displacement device inflates and/or maintains inflated the cushion device.

Preferably, the cushion device is in fluid communication with an outlet or interior of the fluid displacement device. The fluid displacement device is preferably a blower, turbine or fan driven by an electric motor.

In an embodiment, the mounting arrangement includes a one way valve interposed between the cushion device and the fluid displacement device, the valve being arranged to only allow fluid transmittal from the fluid displacement device to the cushion device.

In another embodiment, the mounting arrangement includes a pressure regulation valve interposed between the cushion device and the fluid displacement device, or between the cushion device and a zone of lower pressure tan the cushion device (such as atmosphere), the valve being arranged to limit pressurisation of the cushion device to a predetermined maximum.

In a further embodiment, the mounting arrangement includes the one-way valve and the pressure regulating valve.

The arrangement preferably also includes other mounting devices produced from foam or other elastomers. These mounting devices can, for example, act as displacement limiting devices when the cushion is not inflated or provide a resilient base for the cushion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of a mounting arrangement according to the invention;

FIG. 2 is a sectional cut away view of the arrangement shown in FIG. 1;

FIG. 3 is a perspective view of a second embodiment of a mounting arrangement according to the invention; and

FIGS. 4 through 15 are schematic side views of third through fourteenth embodiments of mounting arrangements according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a first embodiment of a mounting arrangement 10 according to the present invention. The mounting arrangement 10 includes a fluid displacement device in the form of blower 12. The blower 12 has a rotor 13 rotationally driven by electric motor 14 and an outlet 15.

The underside of the blower 12 is mounted to an inflatable cushion device in the form of open-ended annular membrane 16. The membrane 16 has an internal generally cylindrical orifice 18, a generally planar annular base surface 20 and a curved side wall 22 having a pair of spaced apart internal locating rims 26 adjacent its distal edge.

The blower 12 is formed from two joined casing portions 28 and 30. The casing portion 30 contains the rotor 13 and has a central cylindrical inlet flange 34 for receiving air drawn through the orifice 18. The inlet flange 34 is a light snug fit with adjacent upper wall 35 of the orifice 18,

The casing portion 30 also includes an annular flange 36 and an opening 38. The internal diameter of the membrane sidewall 22 is slightly smaller than the external diameter of the flange 36. The membrane 16 is assembled with the flange 36 by stretching it over the flange 36 and locating the flange 36 between the two locating rims 26. The resilience of the membrane 16 contracts it into sealing engagement with the periphery of the flange 36.

Energising the electric motor 14 causes the rotor 13 to spin. This pressurises the interior of the two housing portions 28 and 30 causing pressurised air (or other breathable gas) to be displaced from a outlet 15 (see FIG. 1). The pressurised air is also displaced through the orifice 38 into interior space 40 defined between the underside of the flange 36 and the interior of the membrane 16.

The mounting arrangement 10 is installed within a CPAP apparatus housing (not shown) wit the underside of the base surface 20 supported on the chassis or some other rigid component of the housing. When the motor 14 is energised the membrane 16 is inflated which raises and supports the blower 12 and the motor 14 away from the housing chassis or the like to isolate vibration produced by the blower 12 and motor 14 from the housing.

A calculation of the lifting or supporting force generated by the membrane 16 is set out below,

1 cm H₂O=98.1 N/m{circumflex over ( )}2

1N=101.9 g

Surface area of membrane 16 with 0.15 m outside diameter and 0.03 m inside diameter=0.0169 m{circumflex over ( )}2.

Combined weight of motor 14 and blower 12=330 g

Force generated by membrane 16: 1 cm H₂O will lift 98.1×0.0169=1.664N or 169.584 g

Therefore 330/168.938=1.945 cm H₂O will be required to lift the motor/turbine assembly.

This pressure is easily achievable by the blower/motor assembly which typically operates in the range of 2-20 cm H₂O when used for treating OSA.

The main advantage of the arrangement 10 is that the membrane 16 is inflated by the blower 12. This overcomes the leakage problems of prior art devices and also obviates the need for a separate dedicated pressurised fluid source.

Another advantage is improved vibration isolation compared with other means as the only direct path for vibration is through the thin, flexible cushion (membrane) walls. The air within the cushion can also absorb vibration as the air particles are excited and dissipate the energy. As a result of the above, the inflatable cushion can be made smaller than, yet still have the same vibration isolating properties as, foam or other elastomers. This is beneficial is minimising the overall size of the CPAP apparatus.

FIG. 3 shows a second embodiment of a mounting arrangement 50 according to the invention. Like reference to those used in describing the first embodiment will be used to indicate like features. The arrangement 50 is similar to the arrangement 10 except for the addition of six inflatable membranes 52 arranged around the side periphery of the blower 12 and motor 14 which farther assist in mounting and locating the blower/motor assembly within the housing of the CPAP apparatus.

FIGS. 4 to 15 show schematic representations of the third to fourteenth embodiments of the invention. In all of FIGS. 4 to 11 the inflatable cushion device is denoted 60, the blower/motor assembly 62, the blower inlet 64 and the blower outlet 66.

The embodiment of FIG. 4 is similar to that shown in FIG. 1 except that it has a conduit 68 connecting the outlet 66 of the blower/motor assembly 62 to the cushion 60 rather than the opening 38. In this embodiment the inlet 64 passes through an interior opening 69 in the cushion 60 similar to the embodiment of FIG. 1.

FIG. 5 is similar to the embodiment of FIG. 4 except the inlet 64 is positioned remote from the cushion 60 which thus requires no internal opening.

FIG. 6 shows a similar embodiment to. FIG. 5 except the blower/motor assembly 62 is arranged on its side relative to the cushion 60.

The embodiment of FIG. 7 is similar to shown in FIG. 4 but with the addition of a one-way or non-return valve 70 disposed between the outlet 66 and the cushion 60.

FIG. 8 is similar to the embodiment shown in FIG. 7 except the non return valve 70 is replaced by a pressure regulating valve 72.

FIG. 9 is similar to the embodiment shown in FIG. 8 with the addition of a bleed conduit 74 which can vent excessive pressure to atmosphere through a pressure regulating valve 76.

The embodiment of FIG. 10 is similar to that shown in FIG. 9 except the conduit 68 between the inlet 66 and cushion 60 does not contain a pressure regulation valve.

The embodiment of FIG. 11 is similar to that shown in FIG. 10 except the bleed conduit 74 and pressure regulation valve 76 vent excessive gas back to the inlet 64 of the blower/motor assembly 62.

The embodiments of FIGS. 7 to 11 have been described and are shown with the cushion device 60, inlet 64 and blower/motor assembly 62 arranged in a similar manner to that shown in FIG. 4. However, these embodiments are equally applicable to the component arrangements shown in FIGS. 5 and 6 also.

The embodiments of FIG. 12 is similar to that shown in FIG. 4 except it includes multiple (two) cushions 60 fed by multiple (two) conduits 68 arranged in parallel.

The embodiment of FIG. 13 is similar to that shown in FIG. 12 except that the multiple (two) cushions 60 are fed by multiple (two) conduits 68 arranged in series.

The embodiment of FIG. 14 is similar to that shown in FIG. 4 except additional components 78 are interposed between the cushion 60 and the blower/motor assembly 62.

The embodiment of FIG. 15 is similar to that shown in FIG. 14 except that an external cushion 60 a supports a casing 80 around the blower/motor assembly 62. Further, inside the casing 80, there is provided a series of cushions 60 b which support the additional components 78 and a cushion 60 c interposed between the additional components 78 and the blower/motor assembly 62.

The embodiment shown in FIGS. 12 to 15 can also include the non-return valves or pressure regulation valves shown in FIGS. 7 to 11.

Although we invention has been described with reference to a preferred embodiment, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. 

I claim:
 1. An apparatus for supplying breathable gas for assisted respiration, the apparatus comprising: a main housing; and a mounting arrangement installed within the main housing, the mounting arrangement being associated with a fluid displacement device and including an inflatable cushion device adapted to support the fluid displacement device and in fluid communication with the fluid displacement device, whereby a portion of the fluid displaced by the fluid displacement device at least one of inflates and maintains inflated the cushion device.
 2. The apparatus according to claim 1, wherein the mounting arrangement is fixed with respect to the main housing.
 3. An apparatus for supplying breathable gas for assisted respiration, the apparatus comprising: a casing portion having a gas flow path between a gas inlet and a gas outlet; a rotor disposed within the casing portion and in fluid communication with and positioned between the gas inlet and the gas outlet; an electric motor coupled to the rotor; and an inflatable cushion structured to support the casing portion and the electric motor thereon, wherein the casing portion includes a lower wall structured to cooperate with the inflatable cushion to form a gas receiving space therebetween, the lower wall providing the gas inlet and having at least one opening formed therethrough in fluid communication with the gas receiving space to thereby at least one of inflate and maintain inflated the inflatable cushion.
 4. The apparatus according to claim 3, wherein at least one of the rotor and the electric motor is positioned above the gas receiving space.
 5. The apparatus according to claim 3, wherein the casing portion includes an upper casing portion and a lower casing portion.
 6. The apparatus according to claim 3, wherein the gas inlet is aligned with the axis of the rotor.
 7. The apparatus according to claim 3, wherein an axis of the opening extends generally parallel to the axis of the rotor.
 8. The apparatus according to claim 3, wherein the inflatable cushion has a generally planar base surface and a curved side wall, the side wall being structured and positioned to engage the lower wall of the casing portion in interlocking relation.
 9. The apparatus according to claim 8, wherein the side wall has a pair of spaced apart locating rims adjacent distal edge of the side wall, the locating rims engaging the lower wall of the casing portion.
 10. An apparatus for supplying breathable gas for assisted respiration, the apparatus comprising: a casing portion having a gas flow path between a gas inlet and a gas outlet; a rotor disposed within the casing portion and in fluid communication with and positioned between the gas inlet and the gas outlet, the rotor having a vertically extending axis; an electric motor coupled to the rotor; and an inflatable cushion structured to support the casing portion and the electric motor thereon, wherein the inflatable cushion is in fluid communication with the casing portion to thereby at least one of inflate and maintain inflated the inflatable cushion.
 11. The apparatus according to claim 10, wherein the casing portion includes an upper casing portion and a lower casing portion.
 12. The apparatus according to claim 10, wherein the gas inlet is aligned with the axis of the rotor.
 13. An apparatus for supplying breathable gas for assisted respiration, the apparatus comprising: a casing portion having a gas flow path between a gas inlet and a gas outlet; a rotor disposed within the casing portion and in fluid communication with and positioned between the gas inlet and the gas outlet; an electric motor coupled to the rotor; and a sealed inflatable cushion having a base surface structured to support the casing portion and the electric motor thereon; wherein the inflatable cushion is in fluid communication with the gas outlet to thereby at least one of inflate and maintain inflated the inflatable cushion.
 14. The apparatus according to claim 13, wherein the base surface is a gas impermeable or non-apertured surface.
 15. The apparatus according to claim 13, further comprising a conduit that connects the gas outlet to the inflatable cushion.
 16. The apparatus according to claim 15, wherein the conduit includes a one-way valve structured to only permit the flow of gas from the gas outlet to the inflatable cushion.
 17. The apparatus according to claim 15, wherein the conduit includes a pressure regulation valve structured to limit pressurization of the inflatable cushion to a predetermined maximum.
 18. The apparatus according to claim 13, further comprising a pressure regulation valve interposed between the inflatable cushion and a zone of lower pressure than the inflatable cushion, the pressure regulation valve being structured to limit pressurization of the inflatable cushion to a predetermined maximum.
 19. The apparatus according to claim 13, wherein the casing portion includes an upper casing portion and a lower casing portion.
 20. An apparatus for supplying breathable gas to a patient mask for assisted respiration, the apparatus comprising: a casing portion having a gas inlet, a main gas outlet, and an auxiliary gas outlet; a rotor disposed within the casing portion and in fluid communication with and positioned between the gas inlet and the main gas outlet, and the gas inlet and the auxiliary gas outlet; an electric motor coupled to the rotor; and an inflatable cushion structured to support the casing portion and the electric motor thereon; wherein the inflatable cushion is in fluid communication with the auxiliary gas outlet to thereby at least one of inflate and maintain inflated the inflatable cushion and the patient mask is in fluid communication with the main gas outlet.
 21. The apparatus according to claim 20, wherein the casing portion includes an upper casing portion and a lower casing portion. 